Tunable coaxial magnetron

ABSTRACT

A coaxial magnetron is provided in which the annular outer coaxial cavity is external of the high vacuum region containing the anode, vanes, cathode, and interaction region. The coaxial cavity is electromagnetically coupled to alternate pairs of the vanes conventionally through slits in the sleevelike anode wall, but is physically separated or isolated therefrom by a ceramic sleeve, suitably alumina, which seals the vacuum within the anode wall but which is permeable to electromagnetic energy. Moreover, the coaxial cavity is maintained under pressure at least as great as atmospheric pressure and, suitably, 35 p.s.i. a. (absolute) with an insulating gas, suitably sulfur hexafluoride. A plurality of dielectric vanes are symmetrically disposed about, mounted rotatably through, and proximate to an annular cavity wall. These vanes have a stem forming the shaft connected centrally of the vanes, together resembling the letter T, mounted with the longer axis of the vane perpendicular to the axis of the cavity. These vanes are connected through the supporting wall by the stemlike portion which has its axis parallel generally to the axis of the cavity. Suitably the dielectric vanes consist of alumina, a high purity aluminum oxide ceramic. The vanes are positionally phased and means are connected to each of the plurality of vanes in synchronism whereby the magnetron is dithered at relatively high rates. This latter means and housing internally are included within the same insulating gas atmosphere as the cavity so that no moving parts extend through a pressure differential.

United States Patent David Edward Blank Mountain View:

Geoffrey Thornber. Sunnyvale: Anthony Peter Wynn, Redwood City, all of, Calif.

[72] Inventors [21 Appl. No 816,751

[22] Filed Apr. 16, 1969 [45] Patented June 29, 1971 [73] Assignee Litton Precision Products Inc.

San Carlos, Calil.

[54] TUNABLE COAXIAL MAGNETRON 25 Claims, 4 Drawing Figs.

[52] US. Cl SIS/39.61, 315/3955, 3l5/39.77, 333/83 [51] Int. Cl HOlj 25/50 [50] Field ofSeareh 3l5/39.77,

Primary Examiner-Herman Karl Saalbach Assistant Examiner-Saxfield Chatmon, .lr.

Atlorneys-Alan C Rose. Alfred B. Levine, Ronald W Reagin and Ronald M Goldman ABSTRACT: A coaxial magnetron is provided in which the annular outer coaxial cavity is external of the high vacuum region containing the anode, vanes, cathode, and interaction region, The coaxial cavity is electromagnetically coupled to alternate pairs of the vanes conventionally through slits in the sleevelike anode wall, but is physically separated or isolated therefrom by a ceramic sleeve, suitably alumina, which seals the vacuum within the anode wall but which is permeable to electromagnetic energy. Moreover, the coaxial cavity is maintained under pressure at least as great as atmospheric pressure and, suitably, 35 p.s.i. a. (absolute) with an insulating gas, suitably sulfur hexafluoride. A plurality of dielectric vanes are symmetrically disposed about, mounted rotatably through, and proximate to an annular cavity wall. These vanes have a stem forming the shaft connected centrally of the vanes, together resembling the letter T, mounted with the longer axis of the vane perpendicular to the axis of the cavity, These vanes are connected through the supporting wall by the stemlike portion which has its axis parallel generally to the axis of the cavity. Suitably the dielectric vanes consist of alumina, a high purity aluminum oxide ceramic. The vanes are positionally phased and means are connected to each of the plurality of vanes in synchronism whereby the magnetron is dithered at relatively high rates. This latter means and housing internally are included within the same insulating gas atmosphere as the cavity so that no moving parts extend through a pressure differential.

TUNABLE COAXIAL MAGNETRON This invention relates to tunable coaxial magnetrons and more particularly to coaxial magnetrons turnable at very high rates.

Magnetrons are well known Electron Discharge Devices which function as a source of oscillatory energy at high frequencies, suitably in the Ultrahigh Frequency Range. As oscillators they have a host of well known applications, some in the laboratory and others in radar systems. Heretofore a variety of devices have been used in conjunction with various types of magnetrons including the vane and strap and coaxial magnetrons for the purposes of rapidly tuning these magnetrons over a wide range of frequencies. These devices have used tuning pins or tuning rods or plungers which are reciprocated in a frequency determining portion of the magnetron. In the coaxial magnetron this tuning has been accomplished by a plunger member which extends into the coaxial magnetron cavity and which is reciprocated back and forth by a motor through suitable gearing to provide the periodic frequency sweep, commonly referred to as dithering".

Certain basic limitations inhere in such present devices. For example, with the plunger or movable cavity wall type of tuning device there is a limitation on the repetition rate with which the reciprocating members can be moved back and forth. Part of this limitation is due to inertia. In turn the plungers are connected to external driving means through metal bellows and therefore include the problems of wear and metal fatigue. As a result prior to the invention it had not been possible in practical coaxial magnetrons to obtain tuning rates up to 400 Hertz with a bandwidth of over 260 Megahertz. In addition to the electrical limitations posed when driven at high rates a more than desirable amount of mechanical vibration is likely to occur. In many applications this vibration induce undesirable results.

Accordingly, it is an object of my invention to provide a coaxial magnetron having a novel tuning arrangement;

It is a further object of my invention to provide a coaxial magnetron tunable at tuning rates and at bandwidths greater than have been heretofore possible;

It is a still further object of my invention to provide a tunable magnetron in which vibration is minimized and in which the inclusion of movable elements in the high vacuum region is avoided.

The foregoing and other objects and advantages of the invention together with its characteristics and mode of operation is better understood from the following detailed description taken together with the figures of the drawing in which:

FIG. 1 illustrates schematically and in cross section a tunable coaxial magnetron which embodies the invention;

FIG. 2 illustrates schematically in cross section a top view of the coaxial cavity and vanes of the embodiment of FIG. 1; and

FIG. 3 illustrates schematically the driving mechanism used in the embodiment of FIG. 1.

Briefly the invention comprises a coaxial magnetron in which the assembly containing the vane, anode, and cathode is maintained in vacuum and in which the outer coaxial cavity is maintained in an insulating gas atmosphere under pressure. The coaxial cavity is electromagnetically coupled to the alternate anode vanes through slits in the anode and through a cylindrical ceramic sleeve. The ceramic sleeve while permeable to microwave frequency energy maintains the vacuum in the cathode and anode assembly separate from the pressurized gas in the cavity resonator. A plurality of dielectric vanes or paddles, as variously termed, are located symmetrically spaced about the torroidal output cavity, are rotatably mounted with a dielectric stem or shafts through an annular cavity wall. The vane shafts are coupled together for synchronized rotation through suitable gear means located behind the cavity wall and in the insulating gas atmosphere to a driving mechanism.

The coaxial magnetron is a well known generator of electromagnetic energy in the ultrahigh frequency spectrum. In

general its elements, construction, location, dimensions, methods of assembly and mode of operation are well known, are adequately described in the literature, and need not be here repeated. Particular reference may be made to the patents to Collier U.S. Pat. No. 2,854,603; to Drexler U.S. Pat. No. 3,034,014; and to Buck U.S. Pat. No. 3,333,148. In view of this general knowledge of the coaxial magnetron the embodiment of the invention illustrated in FIG. 1 is limited to a segmented sectional cross section of a tunable magnetron embodying the invention in order to more clearly and concisely describe and direct the readers attention to those characteristics particular to and distinguishing applicant's invention. Accordingly, the illustration in FIG. 1, many of the conventional elements which are normally included in a complete magnetron assembly is simplified and many elements, such as the high voltage and filament terminals, connectors, cooling fins and permanent magnets are, for clarity, omitted. However, reference may be had to the above-identified patents, to the literature, and to prior art coaxial magnetrons, such as those heretofore manufactured and sold by Litton Industries, Electron Tube Division, San Carlos, California should such conventional details and elements be of interest to the reader. schematically the embodiment of FIG. 1 includes a top pole piece 2 and a bottom pole piece 4, spaced apart a predetermined distance; a cylindrical sleeve of metallic material 6 surrounds the pole piece ends and forms the magnetron anode. The anode includes a plurality of inwardly projecting anode vanes 8 only two of which appear in the figure. As is conventional, these anode vanes are evenly spaced about the inner surface of the anode sleeve and each of the vanes project therefrom to within a predetermined distance of the cathode 10 which is on support 11.-

Coaxially located around the anode 6 is a cylindrical sleeve 12 of dielectric material, suitably a ceramic such as aluminum oxide (Alumina). The Alumina sleeve is not permeable to gas but is permeable to and permits passage of microwave frequency energy. Anode 6 contains a plurality of passages 14, equal in number to one-halfthe number of vanes 8, only one of which are illustrated in the figure. These passages are slitlike and are formed in the anode only between alternate pairs of anode vanes 8. Thus, as is conventional, only one-half of the plurality of anode resonators, formed in the space between adjacent vanes, are electromagnetically coupled by means'of the passages 14 to the surrounding outer coaxial torroidal cavity which is generally represented as 16.

In the illustrated embodiment anode 6 is attached for support at one end to upper pole piece 2 and at the other end is attached to the bottom pole piece 4. These are preferably bonded together. Ceramic sleeve 12 is brazed or brazed to a sleevelike member which in turn is brazed to the bottom pole piece to form an air tight seal and is brazed between a cylindrical sleevelike member 18 and the upper pole piece to form an airtight seal at that end. A ring-shaped body 22 of microwave loss material is conventionally included.

As is conventional in electron discharge devices for electron interaction to occur a high vacuum environment is required. Accordingly, the region surrounded by ceramic sleeve 12 in the area between the cathode and anode and adjacent the pole piece ends is evacuated in the conventional manner and sealed. The ceramic sleeve 12 forms a border which maintains the vacuum within that region while permitting passage of microwave energy from slits 14 external of that high vacuum region. The outer torroidal cavity coaxial with the anode is a necessary element to the proper function of a coaxial magnetron, denoted as 16, is defined, electromagnetically between a first washerlike wall or annular 24 and a second washerlike or annular wall 26, a cylindrical wall 28, and the outer wall of anode 6. I

Effectively the output cavity 16 is divided physically by the ceramic dielectric sleeve 12 into two parts-a small chamber between sleeve 12 and anode 6 which is located within the high vacuum region, and the substantially larger second chamber outside the high vacuum region. Alternatively, of

course, the ceramic sleeve might be directly brazed to the outer anode wall 6 and in that instance the entire output cavity would be outside the high vacuum region and, hence coextensive both physically and electromagnetically. It is also noted that a slight space exists between annular wall 26 and anode 6 at a corner. Since the electric field of the TE mode is of low intensity at that location any leakage is small and negligible.

Attached to cylindrical wall 28 is an output coupling 29 for coupling microwave energy from cavity 16 to external equipment. This output includes a slot 30, waveguide 31, a ceramic window 32 and coupling flange 34. The window 32 is of aluminum oxide and is brazed in place to form a gastight seal. A plurality of dielectric vanes 36 are rotatably mounted in the cavity. As is illustrated, this vane is a generally thin rectangular striplike member 36 mounted with its long or major axis generally. perpendicular to the axis of the anode and is mounted proximate wall 26. Formed integrally with and extending from the midpoint of a long edge of vane 36 is a dielectric stem portion 38. The stem 38 extends through an opening in cavity wall 26 and is fitted within the center of a small gear 44 which in turn is mounted in a bearing 45. Stem 38 thus forms a shaft for the vane. In the preferred embodiment of this invention are eight such vanes, stems, bearings, and gears symmetrically disposed about the bottom wall 26 of coaxial cavity 16 which are better illustrated in FIGS. 2 and 3 to be discussed.

In turn a singular ring gear 46 is located in a groove in mounting plate 48. Ball bearings are included to reduce friction in turning the ring gear. This ring gear, while shown only in cross section, is in the form of a circle and has its teeth along the inner periphery which engages the gears of all of the vanes 36. The ring gear 46 thus couples together for synchronized rotational movement all of the vanes 36. The section numbered 50 schematically illustrated includes both a motor and a tracking device in a housing which is sealed gastight to the outer atmosphere. Leads 51 and 52 extend into the housing by means of a gastight seal. Leads 51 are connected to a source of current for energizing the enclosed motor and leads 52 couple output voltages from the enclosed tracking device to external equipment. The motor shaft 52 is coupled by means of a gear 53 through an intermediate set of gears, gears 54 and 55 both of which are fixed to a common shaft and gear 56. Gear 56 in turn is coupled to one of the vane gears 44. Thus, mechanical-rotation of gear 53 by motor shaft 52 rotates gears 54, 55, and 56 which in turn rotates gear 44 and the ring gear 46. Ring gear 46 in turn rotates all the other vane gears 44 to which it is coupled and accordingly rotates all the vanes in synchronism.

Both the outer housing 50 and the gear support housing 48 are brazed or bonded with the pole pieces or other elements of the magnetron, previously described and as illustrated in FIG. 1, to form a gastight seal. The region of the tube which is surrounded by ceramic sleeve 12, including the anode, is evacuated in a conventional manner through use of a pinch off" tube. In the region including the outer cavity 16 and inner portions of gear housing 48 and the motor, the atmosphere is pressurized with an insulating gas.

The air is evacuated from this second region and a predetermined quantity of an insulating gas, suitably sulfur hexafluoride, is introduced into the coaxial cavity and other areas of the sealed housing to provide a pressurized insulating atmosphere of about 35 pounds per square inch absolute (p.s.i.a.) or in relative terms about p.s.i.

Although FIG. 1 shows only two of the rotatable vanes 36 reference to the schematic cross section top view of the embodiment (with minor omissions) of FIG. 1, shown in FIG. 2, illustrates more clearly the plurality of vanes and their location on annular wall 26' in the coaxial cavity. Where like elements are shown they are similarly labeled to that of FIG. 1, but are primed. FIG. 2 illustrates the anode vanes 8', of which there are 24, the cylindrical anode 6', the 12 slitlike passages 14', which couple alternate ones of the anode resonators to torroidal cavity 16', the cylindrical ceramic sleeve 112', output slot 30 and the cylindrical wall-like portion 28' of the output torroidal cavity 16'. The dielectric vanes 36 are seen to be relatively thin and evenly disposed about bottom wall 26' of the output cavity at the same radial distance, r, from the cylindrical axis, a, of torroidal cavity 16. The stem portions 38 in FIG. I. not visible in this figure, pass through an opening in wall 26 to the gears beneath.

In addition, each of the dielectric vanes is positionally in phase; that is, in the preferred embodiment all of the dielectric vanes present the same impedance or capacitance effect to the electric fields in the outer cavity at any position to which all are rotated. A geometric definition of this positional phase or alignment of the dielectric vanes maybe made as follows: Each of the dielectric vanes has a major axis which forms the same anglea with respect to a surface, s, which surface consists of the locus of all points equidistant by a distance, r, from the cylindrical axis, at, of the torroidal cavity. In FIG. 2 cylindrical axis, a, extends perpendicular to the plane of the drawing. This locus generates a right cylindrical surface, s, of infinite length which extends perpendicular to the plane of the paper and its intersection with the plane of the drawing is represented by the dot-dash lines, labeled, s, forming a circle about cavity 16. Thus, the angle a formed between a corresponding position on any one paddle and surface s is substantially the same angle a formed between that surface s and a corresponding position on any other paddle and, hence, the paddles are positionally phased. Another way of stating this positional phase is that an angle ,8 formed between a radial line, r, drawing from cylindrical axis, a, to the axis of rotation of the vane, and the major axis of the vane, is the same as the angle B formed between the major axis of any other vane and a correspondingly defined radial line.

The gearing arrangement and driving mechanism described in FIG. 1, used to rotate the vanes in synchronism, is more clearly illustrated pictorially in FIG. 3. Again where a corresponding element appears in this figure it is similarly labeled and primed.

In FIG. 3 each of the dielectric stem portions 38' is illustrated in cross section and is joined to corresponding gears 44'. In turn gears 44' are all coupled to ring gear 46 which is threaded along its inner surface. In addition to being coupled to the ring gear, one of the vane gears 44" is coupled to an intermediate driving gear 56'. Gear 56' is in turn coupled through intermediate gears 55', 54' to gear 53' on motor shaft 52'.

As was discussed in FIG. 1, the gear housing surface 48' for this gear assembly is sealed to the mating portions of the magnetron fittings and forms therewith an airtight enclosure. Likewise the outer housing of container 50' forms an airtight seal. As a result only the two power leads 51 for driving the motor and two output leads 52 for the tracking device in FIG. I extend through a sealed connection out of the pressurized gas atmosphere and no moving parts extend through a pressure differential.

As heretofore described, a region of the envelope or housing of the tunable magnetron and most if not all of the torroidal coaxial cavity 16 contains a pressurized insulating gas atmosphere. Suitably, the pressure is about 35 pounds per square inch absolute or slightly greater than two atmospheres in contrast to the high vacuum region in which the cathode and anode are located. In the preferred embodiment the insulating gas is substantially entirely sulfur hexafluoride. However, the gas sulfur hexafluoride SP is one of a group of gases that includes air itself which inhibit arcing or corona discharge which would otherwise occur between the dielectric vanes and cavity walls due to the ionization of atmospheric gases, such as air, in a region of high electric fields. Thus, the installation of the dielectric vane as a practical matter requires for operability the combination of the insulating gas. The selection of a suitable insulating gas involves the consideration of many factors. For example, the gas must have a high dielectric strength and corona on set voltage at a low gas pressure; a low boiling point; the gas must be relatively inert; that is, it must not have chemical activity; the gas must have good thermal stability, must be nonexplosive, nontoxic, and noncombustible and should not have any carbon or conducting particles formed should an electrical arc discharge occur. Particularly, given D as the dielectric strength of air at normal atmospheric pressure (14.7 p.s.i.), the'gas chosen should have a dielectric strength equal to or greater than D,,, thus, D,,,,,=D,,. Even air sealed in the tube at l or 2 atmospheres fulfills this requirement and may be used in other embodiments. Some other practical insulating gases available which may provide a suitable alternative in other embodiments to the sulfur hexafluoride gas are perfluorocyclobutane; oclafluoropropane; dichlorodefluoromethane; hexafloroethane; monochlorotrifluoromethane; nitrogen; nd.. a o ioz ,d z- The operation of a coaxial magnetron or application of the. proper voltages and currents, etc. is well known, described in the literature, and the aforecited reference patents and is not discussed further except where it is pertinent to the mode of operation of the invention. In the coaxial magnetron and necessary to the operation thereof is the setting up within the torroidal cavity of an electric field configuration, denoted as the TE circular electric mode. Secondly, the field configuration is such that where it is coupled to the alternate anode resonators it maintains the magnetron locked in frequency.

without strapping found in conventional magnetrons. This insures operation of the magnetron in the 1r mode.

The size of the output cavity 16 determines its frequency ofresonance. Since the output cavity is very large with respect to the size of the anode resonators the frequency of resonance of the torroidal cavity predominates. Heretofore this phenomenon was used for tuning the coaxial cavity by means of a washer shaped movable plunger which varied the dimensions of this cavity. As is well known, a resonant cavity may be varied in frequency by varying its other electrical characteristics other than by the mechanical movement of a wall; for example, by varying the capacity of the resonant cavity through the use ofa dielectric material which varies its dielectric current in response to a control voltage as is illustratedin the US. Pat. No. 2,752,495 and by the use ofa ferrite material which intersects with the magnetic field to vary the inductance of this cavity in response to the application of suitable control currents illustrated in U.S. Pat. No. 3,333,148. In this .way the electrical characteristics of the cavity are varied to vary its resonant frequency without physical movement. In the present invention a dielectric material which has a constant dielectric constant and which is of an elongated shape. By rotating the vane the quantity of dielec t ric material which is exposed to the lines of the electric field E illustr ated in FIG. 2 varies. Thus, taking the electric field lines E which extends in a circle around cavity 16 it is seen that when the vanes are in the position illustrated in FIG. 2, the dielectric exposed thereto is of an amount equal only to the thickness of the vane. When the vane is rotated by 90the amgunt of dielectric material exposed to the electric field line E is equal to the entire length of the vane resulting in a high capacitance effect. Thus, as the vane is rotated essentially a variable amount of dielectric is provided. This is found to vary the frequency of the magnetron essentially sinusoidally. Accordingly, the tracking generator included in element 50 simply provides a sine wave output as a function of the position of motor shaft 52. As a practical matter, dithering of the magnetron of the invention is provided at least at rates of 400 Hertz and at bandwidths of at least 260 Megahertz.

It is to be understood that the above-described arrangements are intended to be illustrative of the invention and not by way of limitation since numerous other arrangements and equivalents suggest themselves to those skilled in the art and do not depart from the spirit and scope of my invention. For example, the electromagnetic resonator or output cavity 16 discussed in FIG. 1 and which is seen by the electromagnetic energy is, as described heretofore, the cavity bounded by the outer wall of anode 6, the two annular walls 24 and 26 and the outer cylindrical wall 28. In the embodiment of FIG. 1 the electromagnetic cavity is divided into two parts or chambers by the ceramic dielectric sleeve 12. One is a relatively minute chamber which exists in the small annular space between the dielectric sleeve 12 and the outer wall of anode 6 and which is as a consequence in the region in vacuum; and, two, a substantially larger chamber or cavity chamber outside the vacuum region and in the second region filled with insulating gas to which most of the discussion heretofore has been concentrated. The ceramic sleeve hence separates substantially all of the electromagnetic output cavity from the vacuum region and the electromagnetic output cavity is almost or, as hereafter pointed out, entirely coextensive and inclusive of the larger chamber, termed the chamber cavity.

As is apparent from the principles of the present invention, the division of the cavity into two physical cavity chambers; one of which is minute and relatively insignificant is due only to the construction of that practical embodiment. However, it is understood that other alternatives to the details of this construction are possible and within the scope of the invention; for example, the dielectric sleeve 12 could be made of a smaller inner diameter so as to fasten directly to and be flush with the outer surface of anode 6. In that case again the sleeve would divide substantially all of the output cavityfrom the vacuum region and the cavity would consist almost entirely of the chamber cavity external of the region in vacuum.

A further alternative which avoids the use of a sleevelike configuration for the separating dielectric would be to seal in or bond the dielectric ceramic directly in and filling the anode passages 14. In such case the same. functions are accomplished; namely, the dielectric separates physically into a separate cavity chamber portion substantially all of the resonator output cavity physically separate from the vacuum region containing the cathode 10 and anode 6 assemblies while permitting passage between cavity 16 and alternate ones of the anode resonators. And in this construction the output cavity is fully coextensive with the included cavity chamber external ofthe vacuum region.

Accordingly, it is expressly understood that the invention is to be broadly construed within the spirit and scope of the appended claims.

What we claim is;

1. In a coaxial magnetron of the type which includes a cylindrical anode containing a plurality of anode resonators therewithin and coupling slots therethrough to alternate ones of said anode resonators and a toroidallike shaped resonator cavity surroundingsaid cylindrical anode; the invention comprising: an evacuated internal region containing said anode; a gas impervious dielectric sleeve located within said resonator cavity separating substantially all of said resonator cavity from said evacuated internal region to thereby define within said resonator cavity and external of said internal region a toroidal cavity chamber, said dielectric sleeve maintaining in vacuum said internal region and said dielectric sleeve being pervious to electromagnetic energy to permit passage of electromagnetic energy between said cavity chamber and said internal region; a plurality of dielectric vanes rotatably mounted and evenly spaced about an annular wall of said cavity chamber; a corresponding plurality of dielectric shaft means extending through said annular cavity chamber wall, each of said shaft means being coupled to a corresponding one of said vanes for supporting said vanes for rotation; insulating gas means included in said cavity chamber, said gas means being at a pressure at least as great as atmospheric pressure and having a dielectric strength at said pressure at least as great as the dielectric strength of air at one atmosphere pressure; and driving means coupled to said shaft means for rotating said plurality of shafts in synchronism to thereby rotate said plurality of corresponding vanes in synchronism and vary the frequency of said magnetron in dependence thereon.

2. The invention as defined in claim 1 wherein each of said dielectric vanes is located at substantially the same distance, r, from the cylindrical axis, a, of said toroidal cavity, each of said vanes having a major axis aligned at substantially the same angle a with respect to a cylindrical surface, s, said surface, A, being defined as the locus of all points located at a distance, r, from said cylindrical axis, a, to thereby place said vanes positionally in phase.

3. The invention as defined in claim 2 wherein said shaft is a dielectric stem formed integrally with said vane.

4. The invention as defined in claim 3 wherein said gas means comprises sulfur hexafluoride.

5. The invention as defined in claim 4 wherein the pressure at which said gas means is maintained is approximately 35 p.s.i.a.

6. In a coaxial magnetron of the type which includes a cylindrical anode containing a plurality of anode resonators therewithin and coupling slots therethrough to alternate ones of said anode resonators and a toroidallike shaped resonator cavity surrounding said cylindrical anode; the invention com prising: an evacuated internal region containing said anode; dielectric means impervious to gas and pervious to microwave energy located within said resonator cavity separating substantially all of said resonator cavity from said evacuated internal region containing said anode to thereby define within said resonator cavity and external of said internal region a toroidal cavity chamber, said dielectric means maintaining in vacuum said internal region and said dielectric means permitting passage of electromagnetic energy between said cavity chamber and said internal region; a plurality of dielectric vanes rotatably mounted and spaced about an annular wall of said cavity chamber; a corresponding plurality of dielectric shaft means extending through said annular cavity chamber wall, each of said shaft means being coupled to a corresponding one of said vanes for supporting said vanes for rotation in said cavity; insulating gas means included in said cavity chamber, said gas means being at a pressure at least as great as atmospheric pressure and having a dielectric strength at said pressure at least as great as the dielectric strength of air at one atmosphere pressure; and driving means coupled to said shaft means for rotating said plurality of shafts in synchronism to thereby rotate said plurality of corresponding vanes in synchronism and vary the frequency of said magnetron in dependence thereon.

7. The invention as defined in claim 6 wherein each of said dielectric vanes is located at substantially the same distance, r, from the cylindrical axis, a, of said toroidal cavity, each of said vanes having a major axis aligned at substantially the same angle a with respect to a cylindrical surface 5, said surface, 3, being defined as the locus of all points located at a distance, r, from said cylindrical axis, a, to thereby place said vanes positionally in phase.

8. The invention as defined in claim 7 wherein said shaft means comprises a dielectric stem formed integrally with said vane.

9. The invention as defined in claim 8 wherein said gas means comprises sulfur hexafluoride.

10. The invention as defined in claim 9 wherein the pressure at which said gas means is maintained is approximately 35 p.s.i.a.

11. The invention as defined in claim 3 wherein said driving means comprises: a plurality offirst gear means corresponding in number to said shaft means, each of said first gear means being coupled to a corresponding one of said shaft means; an annular-shaped ring gear means coupled to each of said plurality of first gear means for coupling together for concurrent movement said first gear means; motor shaft means; and means coupling said shaft means to anyone of said gear means for driving such gear means whereby rotation of said motor shaft means causes concurrent rotation of said ring gear means and all said first gear means to thereby rotate each of the vanes in said cavity.

12. The invention as defined in claim 6 wherein said dielectric means comprises a sleeve of dielectric material ensleeving said cylindrical anode.

13. The invention as defined in claim 1 wherein said dielectric vanes are evenly spaced from one another.

M. The invention as defined in claim 13 wherein said vanes are positionally in phase.

15. The invention as defined in claim 1 wherein said insulating gas means comprises sulfur hexafluoride.

16. The invention as defined in claim 14 wherein said insulating gas means comprises sulfur hexafluoride.

17. The invention as defined in claim 6 wherein said driving means comprises a plurality of first gear means corresponding in number to said shaft means, each of said first gear being coupled to a corresponding one of said shaft means; an annular-shaped ring gear means coupled to each of said plurality of first gear means for coupling together for concurrent movement all said first gear means; motor shaft means; and means coupling said shaft means to any one of said gear means for driving such gear means; whereby rotation of said motor means causes concurrent rotation of said ring gear means and all said first gear means to thereby rotate each of said vanes within said cavity.

18. The invention as defined in claim 6 further comprising a second region containing said insulating gas means, said second region being coupled to said cavity chamber and wherein said driving means is located within the said second region.

19. The invention as defined in claim 18 wherein said vanes are evenly spaced from one another and said shaft and said vanes are integral to form a T-shaped member.

20. The invention as defined in claim 16 further comprising a second region containing said insulating gas means, said second region being coupled to said cavity chamber and wherein said driving means is located within the said second region.

21. The invention as defined in claim 1 including a second region containing said insulating gas means coupled to said cavity chamber and wherein said driving means is located within said second region.

22. In a coaxial magnetron of the type which includes a cylindrical anode containing a plurality of anode resonators therewithin and coupling slots therethrough to alternate ones of said anode resonators and a toroidallike shaped resonator cavity surrounding said cylindrical anode; the invention comprising: an evacuated internal region containing said anode; a gas impervious dielectric sleeve located within said resonator cavity separating substantially all of said resonator cavity from said evacuated internal region to thereby define within said resonator cavity and external of said internal region a toroidal cavity chamber, said dielectric sleeve maintaining in vacuum said internal region and said dielectric sleeve being pervious to electromagnetic energy to permit passage of electromagnetic energy between said cavity chamber and said internal region; a plurality of dielectric vanes rotatably mounted and spaced about an annular wall of said cavity chamber; a corresponding plurality of dielectric shaft means extending through said annular cavity chamber wall, each of said shaft means being coupled to a corresponding one of said vanes for supporting said vanes for rotation; insulating gas means included in said cavity chamber, said gas means being at a pressure at least as great as atmospheric pressure and having a dielectric strength at said pressure at least as great as the dielectric strength of air at one atmosphere pressure; and driving means located in said second region coupled to said shaft means for rotating said plurality of shafts in synchronism to thereby rotate said plurality of corresponding vanes in synchronism and vary the frequency ofsaid magnetron in dependence thereon.

23. A dither tuned coaxial magnetron including: a first high vacuum portion containing the magnetron electron interaction region; a second gas pressurized portion having an insulating gas atmosphere, said second gas pressurized portion including substantially all of the magnetron toroidal output cavity; a gas impervious sleeve of ceramic material, said sleeve separating substantially all of said toroidal cavity from said high vacuum portion and said sleeve being pervious to electromagnetic energy to permit passage of electromagnetic energy; a plurality of dielectric strips spaced from one another and rotatably mounted in an annular wall of said cavity within said gas pressurized portion; and means mounted within said second gas pressurized portion for rotating each of said dielec tric strips.

24. The invention as defined in claim 23 wherein said dielectric strips are evenly spaced about said annular wall of said cavity; and wherein said strips are positionally in phase.

25 In a coaxial magnetron of the type which includes a cylindrical anode containing a plurality of anode resonators therewithin and coupling slots therethrough to alternate ones of said anode resonators and a toroidallike shaped electromagnetic resonator cavity surrounding said cylindrical anode; the invention comprising: an evacuated internal region containing said anode; a gas impervious dielectric sleeve located within said resonator cavity separating substantially all of said resonator cavity from an evacuated internal region containing said anode to thereby define external of said internal region a toroidal cavity chamber, said dielectric sleeve maintaining in vacuum said internal region and said dielectric sleeve being pervious to electromagnetic energy to permit passage of electromagnetic energy between said cavity chamber and said internal region; a plurality-of eight dielectric vanes rotatably mounted and evenly spaced about an annular wall of said toroidal cavity chamber; said vanes oriented together in positional phase, said positional phase comprising: each of said dielectric vanes being located at substantially the same distance, r, from the cylindrical axis, a, of said toroidal cavity, each of said vanes having a major axis aligned at substantially the same angle, a, with respect to the cylindrical surface, s; said surface, s, being defined as the locus of all points located at a distance, r, from said cylindrical axis, a; a corresponding plurality of dielectric shaft means integral with said vane means extending through said annular cavity chamber wall, each of said shaft means being coupled to a corresponding one of said vanes for supporting said vanes for rotation in said cavity; insulating gas means comprising sulfur hexafluoride included in said cavity chamber, said gas means being at a pressure of approximately 35 p.s.i.a.; a second region coupled to said chamber and containing said insulating gas means and driving means located in said second region coupled to said shaft means for rotating said plurality of shafts in synchronism; said driving means comprising: a plurality of first gear means corresponding in number to said shaft means; each of said first gear means being coupled to a corresponding one of said shaft means; an annular shaped ring gear means coupled to each of said plurality of first gear means for coupling together for concurrent movement all said first gear means; and motor shaft means coupled to anyone of said first gear means, whereby rotation of said motor shaft means causes concurrent rotation of said ring gear means and all said first gear means to thereby rotate each of the vanes within the cavity in synchronism and vary the frequency of said magnetron in dependence thereon. 

1. In a coaxial magnetron of the type which includes a cylindrical anode containing a plurality of anode resonators therewithin and coupling slots therethrough to alternate ones of said anode resonators and a toroidallike shaped resonator cavity surrounding said cylindrical anode; the invention comprising: an evacuated internal region containing said anode; a gas impervious dielectric sleeve located within said resonator cavity separating substantially all of said resonator cavity from said evacuated internal region to thereby define within said resonator cavity and external of said internal region a toroidal cavity chamber, said dielectric sleeve maintaining in vacuum said internal region and said dielectric sleeve being pervious to electromagnetic energy to permit passage of electromagnetic energy between said cavity chamber and said internal region; a plurality of dielectric vanes rotatably mounted and evenly spaced about an annular wall of said cavity chamber; a corresponding plurality of dielectric shaft means extending through said annular cavity chamber wall, each of said shaft means being coupled to a corresponding one of said vanes for supporting said vanes for rotation; insulating gas means included in said cavity chamber, said gas means being at a pressure at least as great as atmospheric pressure and having a dielectric strength at said pressure at least as great as the dieleCtric strength of air at one atmosphere pressure; and driving means coupled to said shaft means for rotating said plurality of shafts in synchronism to thereby rotate said plurality of corresponding vanes in synchronism and vary the frequency of said magnetron in dependence thereon.
 2. The invention as defined in claim 1 wherein each of said dielectric vanes is located at substantially the same distance, r, from the cylindrical axis, a, of said toroidal cavity, each of said vanes having a major axis aligned at substantially the same angle Alpha with respect to a cylindrical surface, s, said surface, s, being defined as the locus of all points located at a distance, r, from said cylindrical axis, a, to thereby place said vanes positionally in phase.
 3. The invention as defined in claim 2 wherein said shaft is a dielectric stem formed integrally with said vane.
 4. The invention as defined in claim 3 wherein said gas means comprises sulfur hexafluoride.
 5. The invention as defined in claim 4 wherein the pressure at which said gas means is maintained is approximately 35 p.s.i.a.
 6. In a coaxial magnetron of the type which includes a cylindrical anode containing a plurality of anode resonators therewithin and coupling slots therethrough to alternate ones of said anode resonators and a toroidallike shaped resonator cavity surrounding said cylindrical anode; the invention comprising: an evacuated internal region containing said anode; dielectric means impervious to gas and pervious to microwave energy located within said resonator cavity separating substantially all of said resonator cavity from said evacuated internal region containing said anode to thereby define within said resonator cavity and external of said internal region a toroidal cavity chamber, said dielectric means maintaining in vacuum said internal region and said dielectric means permitting passage of electromagnetic energy between said cavity chamber and said internal region; a plurality of dielectric vanes rotatably mounted and spaced about an annular wall of said cavity chamber; a corresponding plurality of dielectric shaft means extending through said annular cavity chamber wall, each of said shaft means being coupled to a corresponding one of said vanes for supporting said vanes for rotation in said cavity; insulating gas means included in said cavity chamber, said gas means being at a pressure at least as great as atmospheric pressure and having a dielectric strength at said pressure at least as great as the dielectric strength of air at one atmosphere pressure; and driving means coupled to said shaft means for rotating said plurality of shafts in synchronism to thereby rotate said plurality of corresponding vanes in synchronism and vary the frequency of said magnetron in dependence thereon.
 7. The invention as defined in claim 6 wherein each of said dielectric vanes is located at substantially the same distance, r, from the cylindrical axis, a, of said toroidal cavity, each of said vanes having a major axis aligned at substantially the same angle Alpha with respect to a cylindrical surface s, said surface, s, being defined as the locus of all points located at a distance, r, from said cylindrical axis, a, to thereby place said vanes positionally in phase.
 8. The invention as defined in claim 7 wherein said shaft means comprises a dielectric stem formed integrally with said vane.
 9. The invention as defined in claim 8 wherein said gas means comprises sulfur hexafluoride.
 10. The invention as defined in claim 9 wherein the pressure at which said gas means is maintained is approximately 35 p.s.i.a.
 11. The invention as defined in claim 3 wherein said driving means comprises: a plurality of first gear means corresponding in number to said shaft means, each of said first gear means being coupled to a corresponding one of said shaft means; an annular-shaped ring gear means coupled to each of saId plurality of first gear means for coupling together for concurrent movement said first gear means; motor shaft means; and means coupling said shaft means to anyone of said gear means for driving such gear means whereby rotation of said motor shaft means causes concurrent rotation of said ring gear means and all said first gear means to thereby rotate each of the vanes in said cavity.
 12. The invention as defined in claim 6 wherein said dielectric means comprises a sleeve of dielectric material ensleeving said cylindrical anode.
 13. The invention as defined in claim 1 wherein said dielectric vanes are evenly spaced from one another.
 14. The invention as defined in claim 13 wherein said vanes are positionally in phase.
 15. The invention as defined in claim 1 wherein said insulating gas means comprises sulfur hexafluoride.
 16. The invention as defined in claim 14 wherein said insulating gas means comprises sulfur hexafluoride.
 17. The invention as defined in claim 6 wherein said driving means comprises a plurality of first gear means corresponding in number to said shaft means, each of said first gear being coupled to a corresponding one of said shaft means; an annular-shaped ring gear means coupled to each of said plurality of first gear means for coupling together for concurrent movement all said first gear means; motor shaft means; and means coupling said shaft means to any one of said gear means for driving such gear means; whereby rotation of said motor means causes concurrent rotation of said ring gear means and all said first gear means to thereby rotate each of said vanes within said cavity.
 18. The invention as defined in claim 6 further comprising a second region containing said insulating gas means, said second region being coupled to said cavity chamber and wherein said driving means is located within the said second region.
 19. The invention as defined in claim 18 wherein said vanes are evenly spaced from one another and said shaft and said vanes are integral to form a T-shaped member.
 20. The invention as defined in claim 16 further comprising a second region containing said insulating gas means, said second region being coupled to said cavity chamber and wherein said driving means is located within the said second region.
 21. The invention as defined in claim 1 including a second region containing said insulating gas means coupled to said cavity chamber and wherein said driving means is located within said second region.
 22. In a coaxial magnetron of the type which includes a cylindrical anode containing a plurality of anode resonators therewithin and coupling slots therethrough to alternate ones of said anode resonators and a toroidallike shaped resonator cavity surrounding said cylindrical anode; the invention comprising: an evacuated internal region containing said anode; a gas impervious dielectric sleeve located within said resonator cavity separating substantially all of said resonator cavity from said evacuated internal region to thereby define within said resonator cavity and external of said internal region a toroidal cavity chamber, said dielectric sleeve maintaining in vacuum said internal region and said dielectric sleeve being pervious to electromagnetic energy to permit passage of electromagnetic energy between said cavity chamber and said internal region; a plurality of dielectric vanes rotatably mounted and spaced about an annular wall of said cavity chamber; a corresponding plurality of dielectric shaft means extending through said annular cavity chamber wall, each of said shaft means being coupled to a corresponding one of said vanes for supporting said vanes for rotation; insulating gas means included in said cavity chamber, said gas means being at a pressure at least as great as atmospheric pressure and having a dielectric strength at said pressure at least as great as the dielectric strength of air at one atmosphere pressure; and driving means located in said second region coupled to Said shaft means for rotating said plurality of shafts in synchronism to thereby rotate said plurality of corresponding vanes in synchronism and vary the frequency of said magnetron in dependence thereon.
 23. A dither tuned coaxial magnetron including: a first high vacuum portion containing the magnetron electron interaction region; a second gas pressurized portion having an insulating gas atmosphere, said second gas pressurized portion including substantially all of the magnetron toroidal output cavity; a gas impervious sleeve of ceramic material, said sleeve separating substantially all of said toroidal cavity from said high vacuum portion and said sleeve being pervious to electromagnetic energy to permit passage of electromagnetic energy; a plurality of dielectric strips spaced from one another and rotatably mounted in an annular wall of said cavity within said gas pressurized portion; and means mounted within said second gas pressurized portion for rotating each of said dielectric strips.
 24. The invention as defined in claim 23 wherein said dielectric strips are evenly spaced about said annular wall of said cavity; and wherein said strips are positionally in phase.
 25. In a coaxial magnetron of the type which includes a cylindrical anode containing a plurality of anode resonators therewithin and coupling slots therethrough to alternate ones of said anode resonators and a toroidallike shaped electromagnetic resonator cavity surrounding said cylindrical anode; the invention comprising: an evacuated internal region containing said anode; a gas impervious dielectric sleeve located within said resonator cavity separating substantially all of said resonator cavity from an evacuated internal region containing said anode to thereby define external of said internal region a toroidal cavity chamber, said dielectric sleeve maintaining in vacuum said internal region and said dielectric sleeve being pervious to electromagnetic energy to permit passage of electromagnetic energy between said cavity chamber and said internal region; a plurality of eight dielectric vanes rotatably mounted and evenly spaced about an annular wall of said toroidal cavity chamber; said vanes oriented together in positional phase, said positional phase comprising: each of said dielectric vanes being located at substantially the same distance, r, from the cylindrical axis, a, of said toroidal cavity, each of said vanes having a major axis aligned at substantially the same angle, Alpha , with respect to the cylindrical surface, s; said surface, s, being defined as the locus of all points located at a distance, r, from said cylindrical axis, a; a corresponding plurality of dielectric shaft means integral with said vane means extending through said annular cavity chamber wall, each of said shaft means being coupled to a corresponding one of said vanes for supporting said vanes for rotation in said cavity; insulating gas means comprising sulfur hexafluoride included in said cavity chamber, said gas means being at a pressure of approximately 35 p.s.i.a.; a second region coupled to said chamber and containing said insulating gas means and driving means located in said second region coupled to said shaft means for rotating said plurality of shafts in synchronism; said driving means comprising: a plurality of first gear means corresponding in number to said shaft means; each of said first gear means being coupled to a corresponding one of said shaft means; an annular shaped ring gear means coupled to each of said plurality of first gear means for coupling together for concurrent movement all said first gear means; and motor shaft means coupled to anyone of said first gear means, whereby rotation of said motor shaft means causes concurrent rotation of said ring gear means and all said first gear means to thereby rotate each of the vanes within the cavity in synchronism and vary the frequency of said magnetron in dependence thereon. 